To Julie's point, some parents are growing more sensitive to the condition due to more positive programming on TV. Add the research capabilities of the internet, and you will have more trans kids both able to act upon their GV (gender variance) condition, and thus will be able to stand up and be counted.
If parents do the research, and can get their child into a qualified gender therapist, then you will see a whole generation of better balanced kids who are able to transition at earlier and earlier ages.
This sounds like a win-win to me. Children, however, need the support of the school districts for anti-bullying rules. Teachers and administrators need to be trained to teach the other children how to be sensitive to their GV classmate. More and more school districts are starting to "get it".
I do think, in the 1950-60's, that their were more effects of environmental and medicinal contamination of children in the womb. DES(?) administered by doctors for women's difficult pregnancies, in addition to chemicals having made their way into the groundwater. Both toxins caused estrogen to spike within women and children in utero, interfering with 'normal' fetus development.
Again, seems like we have both nature and nuture things happening....